Mechanism for truing and dressing grinding wheels



n 1929. F. J. HOHNHORST ET AL MECHANISM FOR TRUING AND DRESSING GRINDING WHEELS Filed June '15, 1925 2 Sheets-Sheet 1 INVENTORS.

June 4, 1929. oHN o s-r ET AL- 1,715,835

MECHANISM FOR TRUING AND DRESSING GRINDING WHEELS Filed June 15, 1925 2 Sheets-Sheet 2 9/ INVENTORS.

Patented June 4, 1929.

UNITED STATES 1 ,715,835 PATENT OFFICE.

FERDINAND J. HOHNHORSTAND FERDINAND T. KROEGER, 0F COVINGTON, KENTUCKY.

MECHANISM FOR TRUING AND DRESSING GRINDING WHEELS.

"Application filed June 15, 1925.. Serial No. 37,080.

plification 'upon the devices shown, described and claimed in our Letters Patent No.

1,526,496, dated February 17, .1925, and our copending applications for patents respectivelyfiled in the United States Patent Oflice on January 30, 1925, as Serial No. 5707, and on February 16, 1925, as" Serial No. 9412, all on improvements in mechanism for truing and dressing grinding wheels. 7

We have found that in precision grinding or polishing, it is essential for obtaining best results that the grinding wheel shall be maintained in its true form, for instance, cylindrical form, and that for accomplishing this, it is advisable to employ an abrading wheel .located at an angle with relation to the plane of the grinding wheel, and to so mount the abrading wheel that vibrations thereof during the grinding or polishing are avoided, and to provide a mounting for the abrading wheel so constructed and arranged that its parts are simple, strong and durable, and are capable of being quickly replaced for repair and renewal of the parts, features especially important in rapid reproduction work as, for instance, in the automobile field.

It is the object of our invention therefore to provide a novel truing and dressing device of this character and having the advantages stated.

It is the object of our invention, further,

to provide an abrading wheel rotatable upon 'a plurality of sets of ball-bearings, each of which sets comprises radially and oppositely disposed end thrust ball-bearings, and pro jecting the respective sets ofball-bearings within the abrading wheel between the planes of the sides of the latter; further, to provide novel means for mounting. the ball-bearings so that the same may be readily and quickly removed; and, further, to provide novel means for clamping the axle which supports the ball-bearings and abrading wheel and the projecting guard for the abrading wheel in place for quick attachment and removal.

The invention will be further readilyi1nderstood from the following description and claim, and from the drawings, in which latter: I I

Fig. 1 is a plan view of our improved device applied to an exemplified grinding machine, partly broken away.

. Fig. 2 "s a cross-section of the same, taken on the line 22 of Fig. 1, and partly broken 7 away.

Fig. 3 is a plan view oftheabrading wheel and its mounting.

Fig. 4 is a vertical axial section of the same, taken on the line 44. of Fig. 3; and, Fig. 5 is a vertical section of the same, taken on the line 55 of Fig. 3. v p

We have exemplified our invention as employed in connection with a so-called grinding orpolishing machine employing arotary grinding wheel 11 for effectingthe grinding or polishing.

The work to be ground or polished, which may for instance be a shaft, is arranged to be.

placed between suitablecenters 12, 13, of which l2 may exemplifya head-centenar- 1 ranged to be rotated by suitable driving means,'as by a pulley 14;. A usual quill 15 in which the head-center is supported-in usual manner is ournaled in a bearing 16 of a headstock 17 ,slidable laterally on guideways 18, 19, of a table 20.

The tail-center 13 is mounted in a suitable sleeve 21, movable axially in a bearing 22, in usual manner, the bearing being on a tailstock 23 laterally adjustable on the guideways 18, 19, of the table 20.

The table is exemplified as pivotally mounted by a pivot 25 on a saddle 26, which has i lateral reciprocating motion imparted thereto by power'means, in usual manner, as by a pinion 27', suitably 'driven, meshing with the rack 28 extending lengthwise of the saddle and fixed to the saddle. The saddle is slidable on guideways 29, 30, on the frame 31 of the machine.

Thegrinding wheel 11 is suitably fixed toa shaft 34 journaled in bearings 35 of a slide 36, adjustable toward and from the worktable on guideways 37, by any suitable means.

the; slide being arranged to be clamped by means of suitable T'-bolts and nuts 38, the heads of the T-bolts coacting with the'T-slot 39 in the frame, and the nuts clamping the slide to the frame. The shaft is rotatable in suitable manner, as by a belt passing about suitable pulleys 4:0, 41, fixed to the shaft.-

In theexemplification, the work located between the centers may be caused to reciprocate wheel having reciprocations imparted to it. I We have instanced the abrading parts as act- 7 ing on the grinding wheel in the absence of work between the centers. The grinding machine may be. of any desirable construction.

The rotary abrading part is exemplified as 1D abrading wheel as. The abrading wheel is preferably of a texture much harder than the grinding wheel and of smaller diameter than the diameter of the grinding wheel on which it operates. The rotation imparted to the grinding wheel is instanced as in the direction of the arrow a, while the rotation imparted to the abrading wheel through the medium of the grinding wheel is instanced. as in the direction of the arrow 6. The abrading wheel is normally quiescent, and rotation is imparted to it by the rotation of the grind ing wheel with which it is placed in contact during the truing or dressing operation.

The grinding wheel during operation becomes impregnated with particles of dirt or metal from the work being operated on, and becomes comparatively glossy and thereby loses its grinding eilect, its granular structure also becoming dull at the grindingi' ace, thereby reducing its grinding or polishing properties. I

By means of our invention, particles 01" dirt and metal are removed from the grinding surface of the grinding wheel by coaction of the rotary abrading wheel therewith, with the plane of the abrading wheel preferably located atan angle to the plane of the grin'ding wheel, whereby to clear the recesses and pores in the grinding surface, and for sharpenmg the particles or grains in the abradin surface, by endwise passage between a? grinding wheel and the abrading wheel. while at angular relations with each other and in contact with each other. i

A swirling action of the ahrading surface of the abrading wheel upon the grinding surface the grinding wheel is therebv produced in order to clean the interstices or pores of the grinding wheel by brushing out the particles of dirt or metal which maybe lodged therein. The more nearly parallel the plane of the abrading wheel is to that of the grinding wheel, the finer will be the dressing imparted to the grinding wheel, and the greater such. angle is, within limits for producing proper rotation of the abrading wheel by the grinding wheel, the coarser will be the dressing imparted to the grinding wheel. The fineness and coarseness of dressing is-controlled by the angle at which the abrading wheel is placed with relation to the grinding wheel.

- An axle 51 is statihnarily positioned. It is shown as extending laterally from a shank 52, and is fixed thereto, accomplished in the present instance by providing said axle with a. tapered end 53, received in a correspondingly ta ,ered hearing 54 in the end of the shank.

This bearing is exemplified as a clamp bearing, being provided with a-split 55 and a bolt 56 and nut 57 for drawing the checks of the bearing thus formed toward each other, in order to clampthe axle in saidbearing. The axle may also be provided with a thread cd end 58, about which a nut 59 is received, for drawing the tapered end of the axle in axial direction into the bearing for additionally securing the same in place.

A pair 01 sets of ball-bearings 61, 62, are received about the axle. Each of these sets of hail-bearings comprises a plurality of ballbearings, which are combined radial and end thrust bearings, the end thrust portions of the same being projected in opposite directions.

Thus each set of ball-bearings. comprises a double inner raceway 63, and a pair of outer raceways 64, 65, having a series of balls 66, 67, coacting therewith. The inner'raccways are exemplified as provided with annular runways 68, 69, for the balls. The outer raceways are exemplified as having oppositely projected end thrust annular rabhets 70, 71, in which the balls are located.

There is a collar 7 5 about the axle, between the inner racewa-ys of the respective sets of raceways. This collar is preferably axially fastonthe axle. r

There is a spacing-ring between the outer raceways oi the respective sets of race ways.

A shell 81 is received about the ball-bearings. This shell provided with an inwardly projecting annular flange82 at one end thereof, this flangeheing provided with an annular shoulder 83. The ball-bearings are received in the bore or" the shell. The other end of the shell is provided with a threadez'l inner periphery 84, to which a plug 85 is threaded. The inner end or: the plug is provided with an annular shoulder 86, and also provided with sockets ST'lor a suitable spanner wrench.

The ouer raceways of the respective sets of ball-bearings and the spacing-ring 76 therebetween are clamped in endwise relation be tween the shoulder Siland the plug 85.

The inner raceways of the respective sets of raceways are received closely about the axle, with the collar therebetween. The inwardly extending flange 82 of the shell is provided with acentral'hole 88, through whichthe axle is received, the axle preferably having close connection with the wall of said hole in order that the interior of the shell mayjform a lubricant cavity 89.

V The said flange is also provided with an inner annular recess 91. and the plug is provided with an inner annular recess 92. These recesses permit just sufficient end playbetween the inner raceways' and outer raceways to prevent binding between said raceways and the balls therebetween, but hold the abradingwheel in endwise relation on the axle.

The plug- 85 closes the end of theshell and may be provided with a central recess 93 so as to avoid danger of contact between the end of the axle-and said plug. I 7 V The lubricant, for instLnQe, oil or, light grease, may be supplied through a passage 94 in the axle. This passage is exemplified as a central bore extending through the axle and discharging into the cavity into the shell at one end and arranged to receive the lubricant through its other end. This other or outer end of the axle may, if desired, be provided with a threaded recess 95 to which a suitable force feed pipe for a lubricant may be attached, and which may be closed by a suitable plug 96 after the lubricant has been supplied. A

The shell is also provided with an outwardly extending annular flange 97. The other end of the shell may be threaded at its outer periphery, as shown at 98, for receiving a nut 99 thereover, for clamping the abrading wheel 45 in place. A washer 100 may be interposed between the abrading wheel and the nut, and the abrading wheel and said nut clamped between the outwardly extending flange 97 and the nut 99.

A protecting guard 101, which partly encompasses the abrading wheel, may be pro vided. It is shown as having flanges 102. 103, at the respective sides of the abrading wheel, and a top 104 connecting said flanges. Lugs 105, 106, are shown provided for securing the guard in place, effected for instance by a bolt 107 received through a hole in the lug and threaded into the shank. The bolt 56 is shown extending through a hole in the lug 106, this lug being clamped in place simultaneously with the clamping of the clampbearing 54. The part of the shank to which the axle and the guard are secured, is shown square, forming a head 108, and the shank is shown cylindrical, so that it may be turned in its securing means for locating the plane of the abrading wheel in desired relation to the plane of the grinding wheel.

The shank 52 is of heavy and substantial nature. and is arranged to be rigidly secured in place on the grinding machine. The examplified means for fixing the shank inplace comprise the following, instrumentalities: The table of the grindingor polishing machine is provided with a guide 111 and a rail 112. A clamp 113 isprovided with a jaw 114 coacting with the guide, and a clamping means, the latter comprising a jaw 116 having an inclined face 117 on the body of the clamp and a clamp-plate 118, the inclined face and the clamp-plate being arranged to clamp upon the rail 112.

A stem 121 is located in the bearing 122 of r the clamp. An adjustingnut 125 and a lock nut 126 are received over the threaded end 127 of said stem. Said stem is provided with a flattened head. 129, a fork 1800f a handle 131 being received about said head and articurail, causing clamping of the jaw upon said rail.

The body of the clamp is provided with a bearing 145, shown as a clamp-bearing, in which the shank 52 is received and rigidly held, the clamp-bearing being clamped to the shank by means of bolts 146, received through holes of a cheek 148, and threaded in threaded holes of a cheek 150, the cheeks being located at the respective sides of the split 151 in said clamp-bearing, which is thereby constituted a split-bearing. The shank may be rotatively positioned in the bearing 145 for presenting the abrading wheel in a plane at the desired angle to theplane of the grinding wheel,

dependent on the character of truing, dress ing or polishing to be accomplished, and the shank clamped in said bearing in such relation.

If desired there may be an abrading wheel at each side of the shank'52, the said abrading wheels arranged in angular relation to each other, as disclosed in the aforesaid patent and applications.

It has been found that in machines of this character, especially in 'machines employed in intensive grinding as in the automobile field, the parts are subjected to rapid wear, and that the abrading wheel is subjected to great end strains, and that the operation of the abrading wheel takes place in the presence of the abrasive refuse from the abrading wheel and the grinding wheel, all of which tend to create quick wear in the parts of the abrading device.

In order to minimize such wear, and to provide an abrading device in which the parts a are quickly repaired or renewable, and to provide a device in which tortional or tilting strains upon the abrading'wheel are resisted to greatest extent, and chattering of the abrading wheel is avoided, We have provided the means herein shown and described, wherein the abrading wheel rotates about a plurality of sets of ball-bearings, with the respective sets or ball-bearings projected within the bore of the abrading wheel, so that the abrading wheel shall have long bearings, and so that endwise and tilting strains on the abrading wheel may be resisted by a plurality of end thrust ball-bearings, projected in opposite directions and further, provide means whereby ball-bearings are enclosed, and whereby lubrication of the same is readily provided, and so arranged that the oil or lu brie-ant therein will also arrest the passage of abrading dust and dirt thereinto.

'20 Having thus fully described ourinvention wheel, and bolts securing said safety-guard to said shank one oi said bolts received through said clamp-bearing; and a part of said safety-guard forsimultaneously clamping said bearing and said safety-guard.

In testimony whereof, we have hereunto signed our names.

FERDINAND J. HOHNI-IORST. FERDINAND J. KROEGER. 

